I. Field of the Invention
The present invention relates generally to position controllers and more particularly to a time modulated position controller particularly adapted for use with variable area turbochargers.
II. Description of the Prior Art
Position controllers adapted to mechanically position an actuator with respect to an analog signal have gained wide use and acceptance throughout industry in many different applications. For example, in one particular application, a position controller is utilized to control blade pitch in a variable area turbocharger. For maximum turbocharger power and efficiency the pitch of the turbine blades must be varied as a function of the rotational speed of the engine.
Heretofore position controllers for changing the blade pitch in variable area turbochargers have proven to be not only expensive to construct, but also inadequate in operation. One major disadvantage of the previously known position controllers is that operating conditions other than the engine rotational speed, such as aerodynamic loading, affected the position of the position controller. Since for maximum efficiency it is most desirable to have the position controller only responsive to the rotational speed of the engine, these previously known position controllers have resulted in lower engine power and efficiency and resultant fuel waste.